1. Field of the Invention
This invention relates to an alignment apparatus for an exposure apparatus used in the semiconductor manufacturing process.
2. Related Background Art
An alignment apparatus is known in which an alignment apparatus is known in which an alignment illuminating light from an alignment light source is directed onto a reticle having a first alignment mark through an optical system having a vibratory mirror and also onto a substrate to be projected having a second alignment mark through a projection lens and the reflected light from each mark produced by the alignment illuminating light is caused to branch off by the use of beam splitter disposed between the vibratory mirror and the reticle and a photoelectric converter for receiving the scattered light component of the reflected light is disposed at a position in the branching-off optical path which is conjugate with the conjugate position of the pupil of the projection lens.
In the prior art as described above, the alignment illuminating light and the alignment detection light are attenuated in the beam splitter portion by the beam splitter being inserted and further, the optical system of a light receiving system is added in the branching-off optical path of the beam splitter, and this has led to the problem that the entire alignment apparatus becomes complex.